Dexterity Posted February 27 Posted February 27 I know I need to use a 1:1 molar amount. BUT calcium hydroxcide is BARELY soluble in water, so instead of using lime water...will milk of lime work? Like I make a milk of lime slurry with 1 mole calcium hydroxcide THEN add one mole of sodium or potassium carbonate...and stir for a while and wait for the calcium carbonate to drop out... Will this work and produce sodium hydroxcide, which is souble in water. Then I just decant or filter out the precipitation?
exchemist Posted February 27 Posted February 27 On 2/27/2025 at 2:47 AM, Dexterity said: I know I need to use a 1:1 molar amount. BUT calcium hydroxcide is BARELY soluble in water, so instead of using lime water...will milk of lime work? Like I make a milk of lime slurry with 1 mole calcium hydroxcide THEN add one mole of sodium or potassium carbonate...and stir for a while and wait for the calcium carbonate to drop out... Will this work and produce sodium hydroxcide, which is souble in water. Then I just decant or filter out the precipitation? Expand I'm not familiar with milk of lime. Isn't it just another word for lime water?
studiot Posted February 27 Posted February 27 On 2/27/2025 at 2:47 AM, Dexterity said: I know I need to use a 1:1 molar amount. BUT calcium hydroxcide is BARELY soluble in water, so instead of using lime water...will milk of lime work? Like I make a milk of lime slurry with 1 mole calcium hydroxcide THEN add one mole of sodium or potassium carbonate...and stir for a while and wait for the calcium carbonate to drop out... Will this work and produce sodium hydroxcide, which is souble in water. Then I just decant or filter out the precipitation? Expand Solubility constant for calcium carbonate is 1000 time less than for calcium hydroxide, so yes you will remove some calcium carbonate and be left with a sodium carbonate solution, sightly enriched with sodium hydroxide. How are you going to unmix that ?
chenbeier Posted February 27 Posted February 27 It was (is) a common process before electrolysis was invented. https://www.elettronicaveneta.com/en/prodotto/cb-in-103-ev-preparation-of-sodium-hydroxide-by-caustification-of-carbonate/ 1
KJW Posted February 27 Posted February 27 On 2/27/2025 at 9:13 AM, exchemist said: I'm not familiar with milk of lime. Expand I think it's like eye of newt. Welcome to the alchemy forum. On 2/27/2025 at 2:47 AM, Dexterity said: I know I need to use a 1:1 molar amount. BUT calcium hydroxcide is BARELY soluble in water, so instead of using lime water...will milk of lime work? Like I make a milk of lime slurry with 1 mole calcium hydroxcide THEN add one mole of sodium or potassium carbonate...and stir for a while and wait for the calcium carbonate to drop out... Will this work and produce sodium hydroxcide, which is souble in water. Then I just decant or filter out the precipitation? Expand The problem with trying to react undissolved calcium hydroxide is that the solid particles tend to become coated with insoluble calcium carbonate, preventing further access of the calcium hydroxide to the carbonate solution.
Dexterity Posted February 27 Author Posted February 27 On 2/27/2025 at 7:15 PM, KJW said: I think it's like eye of newt. Welcome to the alchemy forum. The problem with trying to react undissolved calcium hydroxide is that the solid particles tend to become coated with insoluble calcium carbonate, preventing further access of the calcium hydroxide to the carbonate solution. Expand So what is the remedy for this? Should I boil the milk of lime? On 2/27/2025 at 9:13 AM, exchemist said: I'm not familiar with milk of lime. Isn't it just another word for lime water? Expand Lime water is clear. Milk of lime is a white solution that will clear if allowed to settle.
chenbeier Posted February 27 Posted February 27 Boil the solution, after cool down filter it, so you get a saturated solution. Settle down is also option, but difficult to decant the solution.
KJW Posted February 27 Posted February 27 On 2/27/2025 at 8:56 PM, Dexterity said: Should I boil the milk of lime? Expand The solubility of Ca(OH)2 decreases with temperature. However, heat may speed up the equilibration. On 2/27/2025 at 8:56 PM, Dexterity said: So what is the remedy for this? Expand The solubility of CaCO3 is actually not very low (0.013 g/L @ 25 °C, although it will be lower in Na2CO3 solution), so the problem I mentioned above may not be as much of a problem as I had suggested. I think heating the mixture with stirring will eventually complete the reaction. In a laboratory setting, one could use a Soxhlet extractor to extract Ca(OH)2 into the flask containing the Na2CO3 solution, though this is probably overkill.
Dexterity Posted February 27 Author Posted February 27 On 2/27/2025 at 9:45 PM, KJW said: The solubility of Ca(OH)2 decreases with temperature. However, heat may speed up the equilibration. The solubility of CaCO3 is actually not very low (0.013 g/L @ 25 °C, although it will be lower in Na2CO3 solution), so the problem I mentioned above may not be as much of a problem as I had suggested. I think heating the mixture with stirring will eventually complete the reaction. In a laboratory setting, one could use a Soxhlet extractor to extract Ca(OH)2 into the flask containing the Na2CO3 solution, though this is probably overkill. Expand Maybe I should use heat. THIS is the way to make it without heat. The famous chemist and physican Paracelsus used his own recipe for alkahest was made of caustic lime, alcohol, and carbonate of potash. The lime and potassium carbonate would turn into potassium hydroxcide.
studiot Posted February 27 Posted February 27 On 2/27/2025 at 2:21 PM, chenbeier said: It was (is) a common process before electrolysis was invented. Expand Electrolysis preparation is apparantly more common in the US than the UK. I do not know about Europe or other places.
Dexterity Posted February 28 Author Posted February 28 On 2/27/2025 at 9:45 PM, KJW said: The solubility of Ca(OH)2 decreases with temperature. However, heat may speed up the equilibration. The solubility of CaCO3 is actually not very low (0.013 g/L @ 25 °C, although it will be lower in Na2CO3 solution), so the problem I mentioned above may not be as much of a problem as I had suggested. I think heating the mixture with stirring will eventually complete the reaction. In a laboratory setting, one could use a Soxhlet extractor to extract Ca(OH)2 into the flask containing the Na2CO3 solution, though this is probably overkill. Expand Have you done a double displacment before. This seems pretty straight forward.
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